This invention relates to the field of pharmaceutical chemistry, and provides an advantageous process for preparing a group of 6-hydroxy-2-(4-hydroxyphenyl)-3-[4-(2-aminoethoxy)benzoyl]benzo[.beta.]thi ophenes. More specifically, the invention relates to methods for preparing novel 2-amino-3-aroyibenzo[.beta.]thiophenes and the subsequent conversion of those thiophenes to the corresponding 2-(4-hydroxyphenyl) derivatives.
Ablehas et al., Can. J. Chem. 65: 1800-1803 (1987) teach the preparation of various 2-aryl-2-hydroxy thioacetamides and their subsequent cyclization to 2-aminobenzothiphenes [benzo[.beta.]thiophenes] with methane sulfonic acid (MeSO.sub.3 H).
Chippendale et al., J. C. S. Perkin I, 1168-1172 (1976) disclose the preparation of certain 2- and 3-(secondary amino)benzo[.beta.] thiophenes and the acylation of 2-(secondary amino) benzothiophenes.
Most of the compounds prepared by the process of this invention are taught in U.S. Patent No. 4,133,814.